You also need to have regular periods (true periods not pill periods). They don't have to be every 28 days, you just need to get them - preferably every 21 to 35 days.

If you come off the pill, treat day one of your withdrawal bleed as day one of your cycle and use precautions till you have a true period and know what you're doing.

If your periods have disappeared concentrate on looking after your overall health. You can record your fertility indicators while you do this but you will need to use condoms or other precautions till your periods return.